Download TEACHERPREPARATIONGUIDE

TEACHER PRE-LAB GUIDE
ENGAGE:
Questions to Ponder: Place the questions on a flip-chart, handout, poster, etc. for
interactive class discussion.
1. How does a human being grow from a single fertilized cell into an individual
containing billions of cells?
Answer: Cells increase their number through a process called cytokinesis or cell
division. Cell division is preceded by nuclear division or mitosis. The genetic
information of the parent cell is reproduced exactly in each daughter cell, whereas
division of the other cell components is not exact.
2. Do all of the cells of the body look like one another? Do they perform the same
jobs?
Answer: There are many different types of cells in the body which serve many different
functions. A nerve cell which conducts electrical messages looks very different from a
cheek cell. Cheek cells are a type of epithelial tissue which are tightly arranged to help
protect against bacterial invasion.
3. Do all cells of the body contain the same genetic information?
Answer: All cells in the body with the exception of the egg and the sperm have identical
copies of an individual’s genetic information. Different genes are activated in different
cell types.
4. How is the genetic blue print that makes you who you are transmitted continually
from one cell to the next?
Answer: The consistent transmission of genetic material from one cell generation to the
next is accomplished through DNA replication during Interphase and division in the
process of mitosis. This nuclear replication and division occurs billions of times with
great accuracy as a human being grows and develops.
5. How long does it take for one parent cell to become two daughter cells?
Answer: In humans, rapidly dividing cells such as skin and gut divide as often as once
a day. Other cells, such as brain and nerve tissue, rarely divide in an adult.
6. Are cells alive?
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Answer: Yes, they are the smallest units of life. They are considered to be living
because they are capable of respiration, nutrient intake, release of waste materials,
reproduction of themselves, movement, responsiveness and other processes which are
characteristic of other living things.
7. What is a cell anyway?
Answer: Cells are sometimes referred to as the basic units of life; they are small
compartments in your body which house your DNA and perform all the essential tasks
to sustain life. They are surrounded by a cell membrane, contain a nucleus surrounded
by a nuclear membrane and have many other organelles performing various functions.
Interactive Microscope:
Review the parts of the microscope and their functions using the interactive microscope.
The Human Cheek Cell Lab:
Materials:
Toothpicks (throw away after use)
Dropper bottle of water
Blank slides
Cover slips (throw away after use)
Methylene Blue dropper bottle
Microscope
Plastic container with dilute bleach solution for used slides
Handout - Answer Key is attached
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EXPLORE:
MODELING:
Materials:
Each of the eight groups need:
4’ long by 2’ wide bulletin board paper
Black, purple and rust yarn: one 100 inch piece of black yarn; one 60 inch piece of
purple yarn; two 30 inch pieces of rust yarn (green twist tie); two 32 inch pieces of rust
yarn (blue twist tie); two 36 inch pieces of rust yarn (red twist tie).
Two 12” pieces of red yarn
Two 12” pieces of blue yarn
Scissors
Scotch tape
Rubber bands
Four red popsicle sticks
Four blue popsicle sticks
PREPARATION:
Set up 8 stations with the materials listed above
PROCEDURE:
Hand out Student Lab Guide 1 (Modeling Mitosis) to each group
MICROSCOPE OBSERVATION OF MITOSIS:
Materials:
Microscope
Prepared slides of Onion Root Tip and Whitefish Blastula
PREPARATION:
Set up 4 microscopes with Onion Root Tip slide at 40X
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Set up 4 microscopes with Whitefish Blastula slide at 40X
PROCEDURE:
Hand out Student Lab Guide 2 (Mitosis Observation) to each group
ANSWERS TO QUESTIONS: STUDENT LAB GUIDE 1
PART A: (pages 2 and 3)
1. Diploid means there are two copies of each chromosome in the cell. For humans,
this means 22 pairs of autosomes (44 total) and one pair of sex chromosomes (2 total).
Most higher organisms are diploid. One chromosome set is inherited from the female
parent through the egg and the other chromosome set is inherited from the male parent
through the sperm (or in plants, through pollen).
2. All human cells are diploid with the exception of the sperm and egg cells. Sperm
and egg cells, also known as gametes, are haploid. They have only one copy of each
chromosome or 23 total chromosomes.
3. A diploid organism, such as a human, has 2 of each kind of chromosome, one from
the father and one from the mother. The matching or homologous chromosome has
similar size and shape, and they carry the same genes arranged in the same order.
However, the particular version (allele) of each gene may not be the same on the 2
homologous chromosomes. For example, considering the homologous pair of red
chromosomes, one of the red chromosomes may have a gene that codes for red hair
color while the other red chromosome has a gene that codes for orange hair color.
4. There are two pairs of homologous chromosomes in the Dibble cell. One pair of red
yarn/popsicle sticks and one pair of blue yarn/popsicle sticks for a total of 4 unreplicated
chromosomes.
5. The two red chromosomes should be circled as a pair; the two blue chromosomes
should be circled as a pair.
6. The homologues are independent of one another. They do not pair with each other
at any time during mitosis.
7. D: all of the above
8. A gene is a section of DNA which will code for a particular protein. An allele is an
alternate form of that gene. For example: One allele of the eye color gene codes for
protein which makes eyes brown. Another allele of the eye color gene codes for a
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protein which makes eyes green. Another example would be the single gene that
contains three different alleles that determine the ABO blood type. Any individual can
receive any two of these three alleles so that a person can be blood type A, B, AB or O.
PART A: (page 4)
1. A. Protein
2. A sister chromatid is one half of a replicated chromosome. A replicated
chromosome contains two identical DNA double strands held together at the
centromere. They are sister chromatids until the centromere breaks, at which point they
become independent daughter chromosomes.
3. The centromere is the site on the replicated chromosome where the two sister
chromatids are attached. It appears as a constriction with two chromosome arms above
and below. The parent strand has replicated along its entire length except at the
centromere.
4. Condensed chromosomes are long pieces of DNA that are highly associated with
and wrapped around protein. Condensation is necessary for nuclear division.
Extended chromosomes are long pieces of DNA that are uncoiled and largely free and
cannot be seen clearly by the naked eye or even with a light microscope.
PART B: (page 5)
1. arose through replication of a parent chromosome.
2. two; two; two; identical
3. There is no pairing of homologous chromosomes during Mitosis. Remind students
that homologous chromosomes pair only during Meiosis so that the chromosome
numbers can be halved to produce the egg and the sperm.
4. 8
5. 92
PART C: (page 7)
1. There are four replicated chromosomes in the Dibble cell, each with two chromatids
held together at the centromere.
2. There would be 46 replicated chromosomes in any human cell undergoing Mitosis
and a total of 92 chromatids.
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PART D: (page 8)
1. Daughter chromosomes are now unreplicated. Each contains a single DNA
molecule.
2. With the exception of rare mutations, Mitosis leads to the formation of identical
daughter chromosomes.
3. Yes! In fact, each daughter chromosome contains one parent strand of DNA with a
newly synthesized complementary strand.
4. In Mitosis the genetic information in the chromosomes of a cell is first reproduced
precisely and then the duplicate sets of information are distributed precisely to two
daughter cells thus preserving the original genetic blue print.
PART F: (page 10 & 11)
1. The parent cell no longer exists. It has divided into two daughter cells. The
cytoplasm and the other organelles that were in the parent cell have been divided
approximately in half for the two daughter cells.
2. The daughter cells are genetically identical and are similar in size, shape and
function.
3. The daughter cells are identical to the parent cell genetically, but they may be slightly
different in size and shape. This is because cytokinesis (division of the cytoplasm) is not
as precise as Mitosis (division of the nucleus).
4. Two things have been accomplished. Mitosis results in a doubling of cell number
and it also accurately passes along the genetic information to the next generation.
5. Your model of a cell was made of paper; the chromosomes made of yarn and
popsicle sticks are only representations of the real things. This allows you to visualize
and manipulate objects that otherwise can only be seen through a microscope. It is
very important to remember that the real things and processes are quite different from
the models.
Prepared by: Dr. Debbie Payne, Ruth H. Liddell, Shirley K. Scarbrough
Alabama State University, Math, Science Partnership, Winter,2013
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